Photoassimilation of organic compounds by autotrophic blue-green algae

Hoare, D. S.; Moore, R. G.

doi:10.1016/0926-6585(65)90192-5

Cited by 58 publications

(35 citation statements)

References 11 publications

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“…However, measurement of the enzyme by the same procedure in Escherichia coli indicated that growth in the presence of the three branched-chain amino acids led to a reduction in specific activity from I 140 to 390 nmol oxoglutarate formed/h/mg. The conversion of va1ine:to leucine by Anabaena variabilis and the findings of Hoare, Hoare & Moore (1967), who used isotopic techniques, that acetate can be converted to leucine in Anacystis nidulans, indicated that the enzyme a-isopropylmalate synthetase was probably present in blue-green algae. Further evidence for this was obtained with extracts of A .…”

Section: Resultsmentioning

confidence: 99%

Branched-chain Amino Acid Biosynthesis in the Blue-green Alga Anabaena variabilis

Hood

Carr

1972

Journal of General Microbiology

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SUMMARYFour enzymes (threonine deaminase, a-acetohydroxyacid synthetase, isopropylmalate synthetase and t ransaminase B) involved in leucine, isoleucine and valine synthesis have been detected in extracts of the blue-green alga Anabaena variabilis and the control of three of the enzymes examined. A new procedure for the determination of transaminase B is described. Threonine deaminase and a-acetohydroxyacid synthetase are subject to feedback control by their end-products. No evidence for the repression of enzyme synthesis in the pathway has been found, although the assimilation and incorporation of exogenous valine and leucine was demonstrated.

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Section: Resultsmentioning

confidence: 99%

Branched-chain Amino Acid Biosynthesis in the Blue-green Alga Anabaena variabilis

Hood

Carr

1972

Journal of General Microbiology

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“…Whereas several workers reported that the enzyme was absent or present only at very low level (15,36), other groups reported that it was responsible for L-Glu synthesis in Anacystis nidulans (30) or that under certain conditions of nitrogen supply it could be an alternative pathway to the glutamine synthetaseglutamate synthase cycle for ammonia assimilation (10,27).…”

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confidence: 99%

Induction, isolation, and some properties of the NADPH-dependent glutamate dehydrogenase from the nonheterocystous cyanobacterium Phormidium laminosum

et al. 1988

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The level of the NADPH-dependent glutamate dehydrogenase activity (EC 1.4.1.4) from nitrate-grown cells of the thermophilic non-N2-flxing cyanobacterium Phormidium laminosum OH-1-p.Cl1 could be significantly enhanced by the presence of ammonium or nitrite, as well as by L-methionine-DL-sulfoximine and other sources of organic nitrogen (L-Glu, L-Gln, and methylamine). The enzyme was purified more than 4,400-fold by ultracentrifugation, ion-exchange chromatography, and affinity chromatography, and at 30°C it showed a specific activity of 32.9 gimol of NADPH oxidized per min per mg of protein. The purified enzyme showed no aminotransferase activity and catalyzed the amination of 2-oxoglutarate preferentially to the reverse catabolic reaction. The enzyme was very specific for its substrates 2-oxoglutarate (K,m = 1.25 mM) and NADPH (Km = 64 ,uM), for which hyperbolic kinetics were obtained. However, negative cooperativity (Hill coefficient h = 0.89) and [SJ0.5 of 18.2 mM were observed for ammonium. The mechanism of the aminating reaction was of a random type with independent sites. The purified enzyme showed its maximal activity at 60°C (Ea = 5.1 kcal/ mol [21.3 kJ/mol]) and optimal pH values of 8.0 and 7.5 when assayed in Tris hydrochloride and potassium phosphate buffers, respectively. The native molecular mass of the enzyme was about 280 kilodaltons. The possible physiological role of the enzyme in ammonia assimilation is discussed.

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“…Attempts to demonstrate isocitrate lyase failed, thus Anabaena can probably not form malate by the glyoxylic acid cycle. There were no indications for the occurrence of the phosphotransacetylase under the assay conditions employed despite the presence of the pyruvate : ferredoxin oxidoreductase [S] and presumably of the acetate thiokinase [30]. Table 5 summarizes the specific activities of several amphibolic enzymes occurring in heterocysts and vegetative cells of Anabaena.…”

Section: Phosphoenolpyruvatementioning

confidence: 99%